acpigen_ps2_keybd: map KEY_HOMEPAGE to 0xaa scancode and TK_HOME

Chromium OS EC has some specialized handling of chromebook specific
function keys on the keyboard top row, these have a function specific
action key code that is exposed to the OS and used to map their
position, and also a specific scancode that has to be mapped to a Linux
event code.

This adds the necessary mapping for KEY_HOMEPAGE, which is going to be
used in new devices.

The scancode picked is 0xe012, which maps to e02a or 0xaa, the
corresponding EC CL is:

https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/7118961

BUG=b:446007724
TEST=flashed and tested on a brox board with chromiumos, checked the
code with evtest

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
Change-Id: I395721a342f507453dae19373df2f189ac1b5dac
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90024
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Caveh Jalali <caveh@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>

src/acpi/acpigen_ps2_keybd.c

@@ -59,6 +59,7 @@ static const uint32_t action_keymaps[] = {
 	[PS2_KEY_DICTATE] = KEYMAP(0xa7, KEY_DICTATE),		/* e027*/
 	[PS2_KEY_ACCESSIBILITY] = KEYMAP(0xa9, KEY_ACCESSIBILITY),	/* e029 */
 	[PS2_KEY_DO_NOT_DISTURB] = KEYMAP(0xa8, KEY_DO_NOT_DISTURB),	/* e028 */
+	[PS2_KEY_HOMEPAGE] = KEYMAP(0xaa, KEY_HOMEPAGE),	/* e02a */
 };
 
 /* Keymap for numeric keypad keys */

src/ec/google/chromeec/ec_acpi.c

@@ -247,6 +247,7 @@ static const enum ps2_action_key ps2_enum_val[] = {
 	[TK_DICTATE] = PS2_KEY_DICTATE,
 	[TK_ACCESSIBILITY] = PS2_KEY_ACCESSIBILITY,
 	[TK_DONOTDISTURB] = PS2_KEY_DO_NOT_DISTURB,
+	[TK_HOME] = PS2_KEY_HOMEPAGE,
 };
 
 static void fill_ssdt_ps2_keyboard(const struct device *dev)

src/ec/google/chromeec/ec_commands.h

@@ -7138,6 +7138,7 @@ enum action_key {
 	TK_DICTATE = 21,
 	TK_ACCESSIBILITY = 22,
 	TK_DONOTDISTURB = 23,
+	TK_HOME = 24,
 
 	TK_COUNT
 };

src/include/acpi/acpigen_ps2_keybd.h

@@ -30,6 +30,7 @@ enum ps2_action_key {
 	PS2_KEY_DICTATE,
 	PS2_KEY_ACCESSIBILITY,
 	PS2_KEY_DO_NOT_DISTURB,
+	PS2_KEY_HOMEPAGE,
 };
 
 #define PS2_MIN_TOP_ROW_KEYS		2